From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7FECFC33CAF for ; Fri, 17 Jan 2020 00:51:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5201920684 for ; Fri, 17 Jan 2020 00:51:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="Mj09KchI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733204AbgAQAvn (ORCPT ); Thu, 16 Jan 2020 19:51:43 -0500 Received: from mail-pl1-f193.google.com ([209.85.214.193]:33413 "EHLO mail-pl1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729887AbgAQAvm (ORCPT ); Thu, 16 Jan 2020 19:51:42 -0500 Received: by mail-pl1-f193.google.com with SMTP id ay11so9119047plb.0 for ; Thu, 16 Jan 2020 16:51:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=rzkCIZyeJNSDUeoW0WDB8K+pRYNo5VpYgzNZyHy++lw=; b=Mj09KchIo1UJC0dxpJ6tTc5JSmvFhWwaMSUlnYQVL2MRTzXFp7fQWkrZ8CGqGFg0OH mY0LixZ82mfeaG8ATkYBdbcO3SDpqeVKjyBXovlIhVQ/SSkzoZmCVi5WWr269yExnBJP uVTFtYm3M5nPXvniklQeotAcoejYmD+P9NlsBliabSreISdc0ZwuqkaAkl837RTeX+TJ 2VszMUnzK6vGi/FAt5ZF5iSaNST5NiP1j4eg7lrgAvgi3JHxtzstj98Kx/jPK+olRFQX dYRQVVT62jCin5QG56eepAXLb5XIjZ60v5sh3ixL/leBvGQ6yfIp9oezS7VwO+qmMmJy SmGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=rzkCIZyeJNSDUeoW0WDB8K+pRYNo5VpYgzNZyHy++lw=; b=BxkTs4v7pRvtctiux1quuaAAxvb9Tdtb90KWguKopYdE+TopfjmrP1TkN2oKDXlUE8 ANQ4BMKJJhDzFxM4j9SL6yTt86HUzjJwHYotovoYd37x9Tt5CBBkI9KU2/UIC6MmyFJV 4wxLBSWL0QM+FQ0BHBtBQvR7rJqrdB9Bea6ZIN3mK7omFwdEjxaz+i9Nufm39F2z/1b4 PEMPde5QWxKriE57XAh/3puCz4llX/Pdjhn+BB9aI9x8UNDJD66GjSb4FKKYToHnYNIb 2JlWnX23LHVhIM6NSdQ6PIErk+Wfut8FKkRxEfliKjvsCDDvzVjk2ZOKT8A7EUra/ujY De0g== X-Gm-Message-State: APjAAAWZzPm5fqyzbKbrP4uj8ZNjDxoe7UGRYFWuPdQkC4Go9Cwun39E mS0VqUZyo6MbTw9b1z9GWLvndoIZN+o= X-Google-Smtp-Source: APXvYqxENfIB4K5OnJQQzypWRzHGjGvL0brA93ricVch/BwLGlMnTSwlaK9+A+6cJqfN6VEobmovDw== X-Received: by 2002:a17:902:8f8e:: with SMTP id z14mr27512057plo.195.1579222302225; Thu, 16 Jan 2020 16:51:42 -0800 (PST) Received: from [192.168.1.188] ([66.219.217.145]) by smtp.gmail.com with ESMTPSA id g11sm25868383pgd.26.2020.01.16.16.51.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Jan 2020 16:51:41 -0800 (PST) Subject: Re: [PATCHSET v2 0/6] io_uring: add support for open/close To: Colin Walters , Stefan Metzmacher , io-uring@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org References: <20200107170034.16165-1-axboe@kernel.dk> <4adb30f4-2ab3-6029-bc94-c72736b9004a@kernel.dk> <4dffd58e-5602-62d5-d1af-343c4a091ed9@samba.org> <9a407238-5505-c446-80b7-086646dd15be@kernel.dk> <1e8a9e98-67f8-4e2f-8185-040b9979bc1a@www.fastmail.com> From: Jens Axboe Message-ID: <18c5a50e-cd7b-cb7f-c159-322486550e8f@kernel.dk> Date: Thu, 16 Jan 2020 17:51:40 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <1e8a9e98-67f8-4e2f-8185-040b9979bc1a@www.fastmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 1/16/20 5:44 PM, Colin Walters wrote: > > > On Thu, Jan 16, 2020, at 5:50 PM, Stefan Metzmacher wrote: >> >> The client can compound a chain with open, getinfo, read, close >> getinfo, read and close get an file handle of -1 and implicitly >> get the fd generated/used in the previous request. > > Sounds similar to https://capnproto.org/rpc.html too. Never heard of it, but I don't see how you can do any of this in an efficient manner without kernel support. Unless it's just wrapping the communication in its own protocol and using that as the basis for the on-wire part. It has "infinitely faster" in a yellow sticker, so it must work :-) > But that seems most valuable in a situation with nontrivial latency. Which is basically what Stefan is looking at, over the network open, read, close etc is pretty nondeterministic. But even for local storage, being able to setup a bundle like that and have it automagically work makes for easier programming and more efficient communication with the kernel. -- Jens Axboe